Impact tool



W. H WEST April 13, 1965 IMPACT TOOL Filed Aug. 8I 1961 Pfarrei@ jz wifH77 'yf United States Patent O 3,177,952 llt/@ACT T001.

Warren H. West, Seabrook Beach, N11., assigner to (Iambridge ThermionicCorporation, Cambridge, Mass., a corporation of Massachusetts Filed Aug.8, 1961, Ser. No. 130,127 Claims. (Cl. 173-121) The lield of thisinvention is that of impact tools and more particularly such toolscapable of delivering impacts in either of two directions.

In the electronic arts, such as for example in the computer elds, use isfrequently made of small taper-piu connectors and terminals. Suchterminals establish electrical Contact by means of frictional engagementbetween correspondingly tapered pins and sockets. The high pressure andsurface wiping action desirable in electrical contacts are created by awedging engagement. To aecomplish the wedging Without resorting torelatively high steady pressure which might damage miniaturizedapparatus, it is preferable that such pins be set in with a sharp impactof short duration.

In some applications, such as the wiring of computer patch panels, it isalso desirable that these pin connectors be easily removable. For thatpurpose also steady high forces should be avoided. The panels into whichthese connections are made are usually made of insulating material ofsomewhat limited strength and they usually have a great number ofperforations so as to accommodate a multiplicity of terminals.Accordingly, if the mass and inertia rather than the strength of thesepanels provide the counteracting force in the extraction of the pinconnectors, the danger of breakage is reduced. An impact will providethe high pressure of short duration needed to utilize the inertia inthis fashion.

Objects of the present invention are to provide an impact tool which candeliver a hammer blow in either of two directions, which delivers blowsin either direction without alteration or adjustment, which is compactwith a minimal number of parts and of light weight, which is highlyreliable, which permits easy reaching into and operation within crowdedsurroundings, which makes eiicient use of the operating force available,and which is of simple and inexpensive construction.

The substance and nature of the present invention can be brieysummarized as to characteristic aspects thereof as follows:

Impact tools according to the invention have an elongate frame carryinga shaft slidably mounted therein and having two abutments, a unitaryhammer or block longitudinally slidable with respect to both the frameand the shaft, latch means for releasably locking the shaft and hammertogether for longitudinal travel, and spring means tending to locate thehammer at a normal position relative the frame. The latch means lock inposition and during relative movement of locked hammer and shaftrelatively to the frame for a given distance on either side of thenormal position. Upon movement beyond the normal position, shaft andhammer are unlocked and the spring means causes the hammer to deliver ablow to one of the abutments. In this manner, the hammer lmass andinertia can be applied in either direction, for setting or pullingrespectively, with the same tool.

These and other objects, inventive aspects, and advantageous resultswill appear from the following detailed description of a practicalembodiment thereof illustrating its novel characteristics.

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The description refers to a drawing in which FIG. l is a plan view inlongitudinal section of a double acting impact tool; i

FIG. 2 is a section on line 2-2 of FIG. l;

FIG. 3 is a plan view of a shaft fitment in engagement with a taper pinterminal.

As shown in the drawing, a shaft 10 is slidably mounted in a sleeve-likeouter frame 12. For purposes of assem.- bly the frame 12 is constructedin three parts, a nose piece 14, a central part 15, and an end cap 16,which parts are threaded each one into the next.

The shaft 10 is urged towards a normal longitudinal position Within theframe 12 by springs 13 and 19 which operate, through washers 20 and 21,on a split ring 22 fitting in an annular groove 23 in the shaft. Thefixed ends of the springs 13 and 19 bear respectively on la shoulder 25on the nose piece 14 and a shoulder 26 on a tubular insert 28 which isprovided for that purpose and is threaded into the rearward end of thenose piece 14.

A hammer Sil is slidably mounted with respect to both the shaft 1@ andthe frame 12, iitting within the frame and externally of and concentricwith the shaft. The movement of the hammer relative the shaft is limitedby an abutment shoulder 55 of the shaft in the one directiom and by anut abutment 56 on the end of the shaft in the other. The nut 56 isprovided with a lock nut 57. The hammer, like the shaft, is urgedtowards a normal position relative the frame 12 by a pair of springs 32and 33. `Washers 35 and 36 are interposed between the springs and thehammer and, by means of shoulders 37 and 38 on the inner surface of thecentral part 15 of the frame 12, these washers limit the expansion oftheir respective springs without restricting the further movement of thehammer 39 in either direction. The fixed ends of the springs 32 and 33bear against the insert 28 and the end cap 16 respectively.

Fitted within a transverse bore 40 in the hammer 30 is a latch key 42.This key also has a bore 43 of diameter sufficient to permit the freepassage therethrough of all adjacent portions of the shaft 10. The shafthas a groove or neck 45 which, when both the hammer 30 and the shaft 1l)are in their respective normal positions, is located within the bore 43of the key 42. When the groove 45 is thus located a spring 47, fastenedby the rivet 48 to the hammer 3@ urges the key 42 laterally so Ithat thebore 43 is eccentric with respect to the shaft and so that the one sideof the key engages the groove 45 in the shaft. The opposing end 46 isthereby caused to project somewhat beyond the bore 40 into a somewhatenlarged portion 49 of the frame 12 having tapered ends 56 and 51.

With the key 42 so disposed the hammer 30 and the shaft are lockedtogether for longitudinal movement within the frame 12. The operation ofthe device is then as follows:

1f, with the parts thus locked, the shaft 10 is longitudinally displacedin either direction relative the frame 12 or, conversely, if the shaftis iixed and the frame is moved, the hammer 3@ also will be displacedwithin the frame, will engage one of the adjacent washers 35 or 36, andwill compress the corresponding spring 32 or 33.

tric relation with the shaft ttl. rThis movement will unlock the hammerfrom the shaft and Will permit the compressed hammer spring to drive thehammer towards its normal position. However, as the shaft 16 is at thispoint also displaced from its normal position the hammer will encountereither the shoulder 55 or the nut 56 before reaching its normal positionand will thereby deliver a sharp hammer-blow in one of the direction tothe shaft `and to the article associated with the shaft or a iitmentthereon.

For use in inserting and extracting components such as taper pinelectrical terminals the projecting end of the shaft has threaded ontoit a iitment 6@ adapted to engage the terminal end of a taper pin 65 asshown in FIG. 3. The pin enters the titment from the side and the groove61, engaging a corresponding collar 66 of the pin, permits either adriving or an extracting force to be applied. t

To set a pin in its socket the fitment is slipped over the end of thecollar and the frame is driven forward until the hammer releases andsnaps forward. The operation in extracting a pin is similar except thatthe frame is drawn back. No adjustment needs to be made. It should benoted that the steady force applied by the operator to the frame 12 andcorrespondingly the bending force applied to a terminal board issubstantially less than the force actually required to properly set orto withdraw va pin because energy is stored in the hammer springs overthe whole displacement of the frame and is released suddenly as animpact of high force and short duration. Being of short duration theactuating force used in making or separating the wedge joint works moreagainst the inertia of a terminal board than against its strength. The:force which the operator of the device must supply is alsocorrespondingly lessened.

Advantages of this device are, like devices of this type generally, thatit is compact and of light Weight and ma easily be operated undercrowded conditions. The particular advantage of the present invention isthat it may, without adjustment or alteration, be used both to set andto extract taper pin electrical terminals. Further advanrtages of thepreferred embodiment shown are that it makes efficient use of thedriving force provided by a single hammer mass and in that the expansionof the opposing hammer spring is limited so that the hammer may beinfluenced solely by the aiding spring.

It should be understood that the present disclosure is for the purposeof illustration only and that the present invention includes allmodifications and equivalents falling Within'the scope of the appendedclaims.

I claim:

1. An impact tool comprising: an elongate frame; a shaft longitudinallyslidable relative to said frame; a hammer longitudinally slidable alongsaid shaft relative to both frame and shaft; spring means tendingresiliently to locate said shaft in the longitudinal direction at anormal position -With respect to said frame; second spring means tendingresiliently to locate said hammer at a normal position with respect tosaid frame; spring-loaded latch means carried by said hammer forreleasably locking said shaft and said hammer together in said normalpositions; a. pair of abutments carried by said shaft and located inspaced relation on either side of said hammer; and means on saidframereleasing said latch means when said hammer is displaced a predetermineddistance in either direction from said normal position; whereby, Whensaid shaft `is displaced in either longitudinal direction with respectto said frame, said hammer will rst be carried with said shaft untilsaid latch is released and then will return towards its normal positionunder the influence of said second spring means thereby delivering ahammer blow to said shaft at one of said abutments.

2. An impact tool comprising: an outer sleeve; a shaft slidably mountedin said sleeve; a hammer slidable on i. said shaft with respect to bothsaid sleeve and said shaft; spring means tending to locate said shaft ata normal position with respect to said sleeve; a spring tending to drivesaid hammer in one longitudinal direction with respect to said sleeve; astop on said shaft for limiting the expansion of said spring withoutrestricting the further movement of said hammer relatively to saidsleeve a second spring tending to drive said hammer in the oppositelongitudinal direction with respect to said sleeve; a second stop onsaid shaft limiting the expansion of said second spring withoutrestricting the further movement of said hammer relatively to saidsleeve, said stops determining a normal position for said hammer; alatch for releasably locking said shaft and said hammer together in saidnormal positions of hammer and shaft respectively; a pair of abutmentscarried by said shaft and located in spaced relation on either side ofthe hammer in normal position; and means on said frame for releasingsaid latch when said hammer is displaced relative to said frame apredetermined distance in either direction from said normal position.

3. An impact tool comprising: an outer sleeve; a shaft slidably mountedin said sleeve; a hammer concentric with said shaft and slidable withrespect to both said sleeve and said shaft; spring means tendingresiliently to locate said shaft in the longitudinal direction at anormal position with respect to said sleeve; a spring concentric withsaid shaft tending to drive said hammer in one irection relative to saidsleeve; a washer interposed between said spring and said hammer; ashoulder on the `inner surface of said sleeve against which the outerportion of said washer can bear for limiting the expansion of saidspring Without restricting the further movement of said hammer; a secondspring concentric with said shaft tending to drive said hammer in theopposite direction relative to said sleeve; a second washer interposedbetween said second spring and said hammer; a second shoulder on theinner surface of said sleeve against which the outer portion of saidsecond washer can bear for limiting the expansion of said second springWithout restricting the further movement of said hammer, said shouldersand said washers determining the normal position for said hammer; aspring loaded latch carried by and transversely slidable within saidhammer for releasabiy engaging said shaft in said normal positions ofshaft and hammer respectively; a pair of shoulders on said shaft locatedin spaced relation on either side of said hammer and frame when thoseparts are in their normal positions; and cam means on the inner surfaceof said sleeve for driving said latch laterally out of engagement withsaid shaft when said hammer is displaced relative to said frame apredetermined distance in either direction from its normal position.

4. An impact tool comprising: an elongate frame; a shaft longitudinallyslidable relative to said frame; a hammer longitudinally slid-able alongsaid shaft relative to both frame and shaft; a plurality of opposingspring means tending to locate the hammer at a normal position withrespect to said frame; means for locking said hammer and said shafttogether in said normal position; means on said shaft for limitinglongitudinal movement in either direction of said hammer relative tosaid shaft and providing impact upon such limiting; and means on saidframe for unlocking hammer and shaft when they are moved relatively tothe frame a predetermined distance in either direction from said normalposition, whereupon the hammer exerts an impact on one of the limitingmeans and hence on the shaft.

5. An impact tool comprising: an elongate frame; a shaft longitudinallyslidable relative to said frame and having impact abutments; unitaryhammer means movable longitudinally of said shaft intermediate saidabutments and capable of delivering hammer blows in either directionagainst said abutments; opposing spring means intermediate said frameand said hammer means capable of exerting a force to initiate saidblows; unitary latch means for locking said shaft to said hammer meansin a normal position and upon movement from said position in eitherdirection for given spring tensioning dis- 5 tances; and means forreleasing said latch means upon displacement of frame and shaft throughone of said distances, initiating a spring blow whose force is directedopposite to the displacement of the shaft.

References Cited bythe Examiner UNlTEDV STATES PATENTS BROUGHTC'N G.DURHAM, Primary Examiner.

NEDWIN'BERGER, Examiner.

5. AN IMPACT TOOL COMPRISING: AN ELONGATE FRAME; A SHAFT LONGITUDINALLYSLIDABLE RELATIVE TO SAID FRAME AND HAVING IMPACT ABUTMENTS; UNITARYHAMMER MEANS MOVABLE LONGITUDINALLY OF SAID SHAFT INTERMEDIATE SAIDABUTMENTS AND CAPABLE OF DELIVERING HAMMER BLOWS IN EITHER DIRECTIONAGAINST SAID ABUTMENTS; OPPOSING SPRING MEANS INTERMEDIATE SAID FRAMEAND SAID HAMMER MEANS CAPABLE OF EXERTING A FORCE TO INITIATE SAIDBLOWS; UNITARY LATCH MEANS FOR LOCKING SAID SHAFT TO SAID HAMMER MEANSIN A NORMAL POSITION AND UPON MOVEMENT FROM SAID POSITION IN EITHERDIRECTION FOR GIVEN SPRING TENSIONING DISTANCES; AND MEANS FOR RELEASINGSAID LATCH MEANS UPON DISPLACEMENT OF FRAME AND SHAFT THROUGH ONE OFSAID DISTANCES, INITIATING A SPRING BLOW WHOSE FORCE IS DIRECTEDOPPOSITE TO THE DISPLACEMENT OF THE SHAFT.